Risk assessment (RA) is a
technique by which the actual or potential adverse effects of
contaminants on plants, animals, or ecosystem integrity can be assessed in a
systematic fashion. Essentially risk assessment asks the question:
How likely is it that damage will be or has been done by contaminants?
What is the Objective of Undertaking a Risk Assessment?
The objective of carrying out a risk assessment is to determine whether any identified
people or ecological
values are likely to be adversely affected by soil, water, or air contamination.
This will enable land managers to make decisions about managing contaminant
risks on sites of concern.
Risk assessment techniques are based on a causal stress-response model in which
a contaminant is transported from a source through a known pathway to a
receptor (people, plants, animals).
This concept forms the basis of risk assessment methods that have been developed
internationally to help manage the impacts of contaminated sites.
Risk assessment for human health is largely similar in scope and methodology
to ecological risk assessment. However in practice, the former may be somewhat simpler due
to the fact that only people are being considered as receptors.
The five components of a risk assessment include:
- Problem Identification
- Receptor Characterisation
- Exposure Assessment
- Toxicity Assessment
- Risk Characterisation.
Risk assessment can be undertaken at three distinct
levels of detail, known as "Tiers'.
At each tier, the five key tasks, are undertaken to
provide information and data. That information and data is then used to make a risk management decision or to decide
whether it is necessary to proceed to the next tier because more detail is
Broadly, the degree
of detail and quality of the data at each tier can be described as:
The role of risk assessment within a broader risk
management framework is illustrated below.